The team at Improv Everywhere — the organizers behind the annual No Pants Subway Ride — hosted another one of their famous events a few weeks ago and just released a video recap of the event.

For our latest mission, over 4,000 people pressed play simultaneously and listened to an mp4 file filled with ridiculous instructions. Participants were instructed to pack a bag with LED lights, reflective vests, and glow sticks and to sit underneath the trees surrounding Prospect Park’s Long Meadow at sunset. The event was a surprise to everyone else in the park. This was all part of our twelfth annual Mp3 Experiment event. The year’s event marked the first time we used an .mp4 file, which included a colorful video component.